Writing and Querying MapReduce Views in CouchDB

Authors View

Finally, let’s save our authors view from Chapter 2 to our new _design/default design document. In this view we will map book documents to key/value pairs of authors and number of pages.

In Futon, select “Temporary view…” from the “View” drop-down menu, and paste the following function into the “Map Function” text box, replacing the existing function:

function(doc) {
   if (doc.authors) {
       for (var i in doc.authors) {
           emit(doc.authors[i], doc.pages);
       }
   }
}

Enter the name of the built-in _stats Reduce function in the “Reduce Function” text box:

_stats

Run the temporary view if you’d like, and then click the “Save As…” button. Enter default again as the “Design Document”, enter authors as the “View Name”, and then click the “Save” button. See Figure 3-5.

Figure 3-5. Saving the authors view in the default design document using Futon

Alternatively, you can update the default design document to add the authors view using cURL:

curl -X PUT http://localhost:5984/books/_design/default -d \ '{ "_id": "_design/default", "_rev": "2-cf88b785f94f2ddc1f9148f425f54f0d", "language": "javascript", "views": { "titles": { "map": "function(doc) { if (doc.title) { emit(doc.title, doc.pages); } }", "reduce": "_stats" }, "formats": { "map": "function(doc) { if (doc.formats) { for (var i in doc.formats) { emit(doc.formats[i], doc.pages); } } }", "reduce": "_stats" }, "authors": { "map": "function(doc) { ...